1. Field of the Invention
This invention relates to a roller, in particular a transport roller, made of an elastic body and a bushing arranged concentrically therein.
Such rollers are known generally and serve, for example, for the transport of paper webs or sheets in copying machines, where the rollers are to be disposed on shafts secured against skew.
2. The Prior Art
From DE-PS 31 40 546 a roller is known which consists of a rigid tubular jacket in which at least one elastic bushing is inserted which is bound by an inner and an outer sleeve of metal and holds the jacket concentrically on a shaft. Here the inner sleeve consists of a clamp-on bushing seated on the shaft with a clamping force directed radially inward while the outer sleeve consists of a clamp-in bushing seated in the jacket with a clamping force directed radially outward.
With this known form of realization a stable connection between roller and shaft is formed by means of commercially available attachment means, and it is not necessary to stay within narrow tolerances between the shaft diameter and the inside of the jacket.
If, however, the roller jacket is to consist of an elastic body, the clamp-in sleeve seated in the jacket with a clamping force directed radially outward will, in the known form of realization, bring about an irregular deformation of the elastic jacket. Even if the roller jacket is remachined in the state mounted in the shaft, a sufficiently exact cylindrical form of the roller jacket can be obtained only for a certain temperature state. With every temperature change, which may fluctuate between -40.degree. C., e.g. during air transport, and +70.degree. C., e.g. during operation of the rollers, a deviation from the cylindrical form of the roller jacket will result due to the clamping force of the clamp-in bushing on the elastic roller material.
But even the clamp-on bushing seated on the shaft with a clamping force directed inwardly, which as a whole is responsible for the necessary skew resistance of the roller, is not without disadvantages. In fact, when the slotted clamp-on bushing is vulcanized in the usual manner, rubber material gets through the slot in the bushing to the inner side of the clamp-on bushing, resulting in deformations requiring remachining. A more serious disadvantage, however, results from the fact that as the rollers are slipped onto the shaft, the metallic clamp-on bushing causes longitudinal ruts in the shaft which ruts are unacceptable in particular where the shaft rotates relative to a bearing.